The invention relates to a drive device for an artificial heart according to the preamble of the main claim.
There is known from European Patent Application 0 531 856 a blood pump which operates in a pulsating manner, and in which there is disposed in the blood pump housing at least one piston driven from a coupling point on a triangular enclosed hypocycloid path, which periodically compresses a blood chamber and again releases it. One corner of the closed triangular hypocycloid path is aligned in the direction of the piston, piston movements arising which consist of a pre-stroke phase, a return stroke phase and a stationary stroke phase. This known blood pump is extremely complex in structure and comprises a large number of individual parts. The movement must be transmitted via a large number of bearings, so that many losses arise. Due to the complex structure, the lifespan of the drive of this pump is unsatisfactory.
U.S. Pat. No. 4,718,903 describes an artificial heart in which there is used as a drive a movable member, upon which pressure plates are secured, and which executes a rolling movement. The movable member has a bidirectional motor with motor housing and an epicycloid gear arrangement, the latter being disposed between the motor and one of two closure parts closing off the housing and rotating relative thereto, in such a way that the motor with housing executes the rolling movement led by guide means and the closure parts, which carry the pressure plates, execute a sliding movement. A reciprocating movement is achieved by reversing the polarity of the motor. Such an artificial heart is complex because of the epicycloid gear arrangement and has a large number of rotating parts. In addition, dead points are present because of the reversal of movement, and the end positions must be recognized for control of the motor.